Conductive wire may be used by vandals to make illicit calls from pay telephones. One end of the wire is inserted through the perforated transmitter cap of the handset, at the central aperture, to puncture the transmitter cover and contact the carbon granules inside. The other end of the wire is inserted in one of the apertures in the receiver cap to contact the metal cover on the receiver, thereby enabling the vandal to make a "free" telephone call. Consequently, a need has arisen for preventing such use of a conductive wire.
Vandal-proof handsets are known, but they fall short of meeting the above-mentioned need. For instance, one type of vandal-proof handset prevents the transducer or receiver cap from being removed from the handset. This is accomplished by providing a protective cover piece having a large central aperture in each transducer or receiver socket. The cover includes axial slots which engage axial ribs on the socket wall to prevent rotation of the cover. A coil spring urges the cover into engagement with the transducer or receiver cap. The cover includes circumferential sawteeth located on its upper surface which cooperate with flexible radial ribs on the cap to allow rotation of each cap when screwed on, but to prevent each cap from being unscrewed.
Other public telephone systems avoid the above-mentioned problem by not using a conventional handset. For example, German Patent Application No. DE 29 41 485 A1, a microphone and loud speaker may be recessed within the telephone housing. Typically, the microphone and loud speaker are positioned within the housing behind a screen or heavy grid. This type of system is problematic in that there is no sense of privacy, anybody in the immediate area surrounding the telephone can hear the user's conversation.
The present invention provides a vandal-proof handset which prevents access to the transducers thereof. An apertured disk is positioned between the transducer and end cap such that the apertures within the disk and the apertures in the end cap are not in registry. Therefore, the transducer is not accessible through any of the apertures in the cap.